Many electric utility transformers are outdoor installations which in the past, have been subjected to possible damage and the creation of power outages due to contact with small mammals and birds. These animals tend to contact the energized conductors leading to transformer insulator bushings thereby creating a short circuit condition.
Most new transformers are now installed with protective, insulating guards on the transformer bushings, and these guards are easily installed by hand since this is done before the new transformer is energized. However, many transformers installed in the past did not include bushing guards of any type, and utilities are striving to retrofit these installations with guards which can be installed without disconnecting the power to the transformer. One such wildlife guard, shown in U.S. Pat. No. 4,845,307 to Cumming et al., is formed by a one piece unit having a lengthwise slot through which the live conductor to the transformer bushing is forced during the installation of the guard. This is somewhat difficult to accomplish from a distance, since the guard must be positively forced over a live conductor, and generally the use of a bucket truck and line crew would be required so that the guard could be brought close to the overhead transformer bushing for installation.
In an attempt to make installation easier, one piece tubular guards formed of two hinged semicircular cylinders have been designed to fit around a bushing and to engage when closed. Again, the problem with these hinged shields or guards is that they must first be carefully positioned relative to the insulator and live wire to the insulator and then the two hinged halves must be forced together around the insulator and locked in the closed position. This again is very difficult to achieve from a distance, and requires the use of a bucket truck and line crew to close the guard.